


Tails and Legs

by angelheartbeat



Series: Septiplier AUs [1]
Category: Septiplier - Fandom, jacksepticeye, markiplier - Fandom
Genre: AU, Fantasy, Fantasy AU, Gay, Green hair, Green tail, Human/Merman, Human/Mythical Creature, M/M, Mythical Creature, Yaoi, human/mermaid, mermaid, merman, merman au, myth, mythical
Language: English
Status: In-Progress
Published: 2016-05-09
Updated: 2016-05-09
Packaged: 2018-06-07 10:40:25
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 6
Words: 3,898
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6800425
Author URL: https://archiveofourown.org/users/angelheartbeat/pseuds/angelheartbeat
Summary: <blockquote class="userstuff">
              <p>Mark is sitting on the beach one day, when he sees someone in the water. They have green hair, and brown stubble, and a sweet Irish accent.</p><p>He seems to be falling in love, except there's one problem.</p><p>Mark can't swim.<br/>The man can't go on land.</p><p>Tails and legs aren't built to be together.</p>
            </blockquote>





	1. Sat on the Beach

**Author's Note:**

> Let's all close our eyes and transport ourselves to an AU where Mark can't swim and Jack may or may not have a tail.
> 
> I actually had the idea for this while on Shoreham beach with one of my best friends, and I'm hoping it's gonna be an ongoing thing. This is my first try at writing fantasy AUS so it might suck. Sorry.

Mark sat on the beach, allowing the waves to wash up around him. Despite his inability to swim, the beach had always been an escape for him, a retreat from humanity. It had become better still once he had discovered this hidden cove, where no one could find him and he could be alone with his thoughts. 

Sighing in contentment and relief, Mark lay back and let the waves surround him. It gave him a thrill, the idea of something he couldn't enter moving around him so carelessly, so simply. With a soft smile, he closed his eyes and drifted off to sleep.

When he awoke, the light was beginning to fade. The water had retreated and his red hair was wet, along with his clothes. That was alright. He often had wet clothes from coming here and falling asleep. 

As he stood up and brushed sand from his body, he heard a low muttering under the crash of the waves. Adjusting his glasses, Mark looked over, shielding his eyes against the glare of the fading sun. By a line of rocks sticking out into the sea, what appeared to be a young man swum in circles, talking to himself. Green hair almost glowed in the disappearing light, and Mark tilted his head.

Moving along the beach, the man's words became clearer, and his movements easier to see. His swimming was smooth and strong, smoother than any Olympic athlete. Mark's heart pounded as he climbed atop the rocks and began to inch out along them, further into the sea. The green-haired man was at the very furthest point, swimming repeatedly in circles. He appeared to be shirtless.

Slipping slightly, Mark felt his heart briefly stop, and he let out a high-pitched squeal that turned into a curse. The swimmer stiffened and slowed to a stop, before turning around slowly. With a confused expression, he swam slowly to where Mark was and just looked at him as he scrambled back onto the rock.

"Who are you?"

They both spoke at the same time, the swimmer's words tinged with a heavy Irish accent. Mark blinked. He hadn't expected that. 

"Why are you on my beach?" Mark asked, his heart racing. The man frowned at him, two bushy eyebrows pulling together. 

"This ain't yer beach, Red," the Irishman said, laughing a little. Mark twitched a little at the nickname, but said nothing. "This is my beach, if anyone's."

"Well, I discovered it, so it's mine," Mark said proudly. The Irish swimmer rolled his eyes.

"Well, what's yer name? I haven't seen ya around here before."

"I'm.. Mark. Mark Fischbach. And you are?"

"Well, really I'm Sean, but I prefer Jack. So, like I said, I haven't seen ya here before. Do ya usually come here?" Mark nodded.

"Yeah, every day. I haven't seen you before."

Mark watched the man as he swum around in circles for a few minutes. The two say in silence, both seemingly lost in thought. 

"Why do you keep swimming? Why don't you come up onto the rocks?" Mark asked after a while. Jack glanced at him.

"I... uh..." he stammered, scratching his head. "Well, that's a tough question to answer." 

Mark tucked his legs close by his chest. 

"I'm listening."

Jack kept swimming in circles, thinking. His brain ticked and whirred, and eventually he whirled around.

"Hey, look! Someone is looking for you!"

"Hm?"

Mark turned his head towards the beach, and heard a gentle splash. When he looked back, the Irish man had disappeared. Cursing himself under his breath, Mark straightened up and began making his way back down the rocks.

"Please be here tomorrow," he whispered to the empty sea, but it simply roared at him, laughing at his efforts. Seagulls wheeled in the sky above him, and he shivered as he realised the sun had disappeared.

Time to head home.


	2. The Next Day

**Summary for the Chapter:**

> Mark waits for Jack.

**Notes for the Chapter:**

> I don't really know where this is heading, but it's a thing.

Mark sat on the beach, legs tucked up beneath him, intently watching the rocks. Feeling his eyes grow heavy, he blinked and shook his head. No falling asleep. Not until he had talked to Jack. The sun seemed to be imperceptibly inching downwards, and Mark let out a yawn.

Suddenly, he pushed himself up. Stretching, he began to walk along the beach towards the rocks where Jack had been the day before. The cool air blew against his face and woke him up slightly, and he blinked with sudden energy.

When he reached the rocks, he began to clamber over them. His heart beat like a drum, a fast but steady beat, and he avoided the particularly slippery patches of seaweed and water. He reached the end and sat there for a while, feet dangling in the water. 

After a while, he got bored and leaned over the edge, keeping a firm grip on the rocks. Looking into the clear water, he could see all kinds of fish swimming about underneath him, and he gasped in shock. Reaching up to scratch his nose, he accidentally dislodged his glasses, and then the fish got a lot blurrier.

A small splash sounded.

"Fuck!" Mark cursed as he stared into the water. "Fuck, fuck, FUCK!" His glasses slowly sunk through the water, becoming further and further until Mark could no longer see them. His view was fuzzy and blurry, and he bit his tongue.

Pulling his feet up and standing up shakily, Mark attempted to move away, in the hopes of getting someone to get them for him. It would be a wrench, losing his private cove, but he needed those glasses back.

As he stood up, however, his foot hit a particularly slimy patch of seaweed and he slipped over immediately. Trying to regain his balance from the slip, Mark felt himself falling backwards. With a shouted curse, he hit the water with a loud splash. 

The instant cold of the water ran shock through his veins and he shuddered. Icy water permeated his very bones and the shock of the freezing temperature, combined with his inability to swim, was too much. His eyes fluttered shut, and his vision went black. With no conscious brain to keep him afloat, the American began to sink through the water, pushed this way and that by the currents. 

* * *

Mark's eyes flew open. He sat bolt upright, and spat out a mix of salty water and sand. Rubbing his eyes, he looked around him and saw his glasses sitting on the sand. He was sitting on the beach, near to the water, with his glasses next to him.

Putting them on and adjusting them, Mark saw the Irish swimmer sitting beside him. Like before, he was shirtless, and his hair was wet and messy. Mark's eyes travelled down his sculpted body, but when he reached his hips he almost yelled out.

Joined seamlessly to the stranger's torso was a scaly, shiny green mermaid tail, flicking in the salty sea spray.

 

**Notes for the Chapter:**

> Sorry for the short chapter, it's midnight and I'm lazy. Also, this was a good note to end on. 
> 
> Anyway, hope you liked! ^-^


	3. What Are You?

**Summary for the Chapter:**

> "What are you?"

**Notes for the Chapter:**

> Yay! Back again!

Mark sprang up, pointing at Jack's tail and stammering for words. Jack turned around to see Mark freaking out, and immediately attempted to hide his tail. It almost glowed, a bright lime green like his hair. 

"Ah, shit," the Irishman muttered under his breath. 

"Y-y-y-You! T-t-tail!" Mark stuttered, pointing shakily at Jack's tail. Sighing, Jack pushed himself back into the water so his tail was fully submerged.

"Better?"

"No! You're a mermaid!" 

Jack sighed, flicking the end of his tail moodily. 

"Mer _man,_ actually. Don't see any boobs here, do ya?" Mark shrugged, his eyes glued to Jack's tail. Jack felt himself heat up, and pulled himself further into the water, starting to leave.

"Wait!"

Looking back, Jack saw Mark moving towards him, water splashing around his ankles.

"Um... would it be possible to see you again? I'd like to talk more. And I can't quite believe this isn't a dream." 

Jack looked at the redheaded man, standing there awkwardly, waves crashing about his feet. 

"Sure."

And with that one word, Jack turned around and dived into the ocean, leaving Mark with sea spray flicking at his legs, glasses reflecting the sun.

* * *

Later that day, Mark found himself inexplicably drawn to the sea. It seemed to call his name, in some strange way. It had never felt like this before.

When he got there, he could see Jack, leaning against a rock. Strange melodies floated through the air, and as Mark drew closer, the words became clearer. It was unlike any song Mark had ever heard, sounding almost like waves hitting the shoreline.

_Sailor please, hear my call,_

_Drive your boat but then you fall,_

_Crying, dying, wish you never came,_

_But you'd end up like this anyway all the same._

Mark walked closer, but Jack chose that point to turn around. As soon as he saw Mark, he turned bright red and hid behind the rock.

"Nice song," Mark said, beginning to climb atop the line of rocks. Jack pulled himself out from the rock and floated there awkwardly.

"It's generally one tha mermaids like ta sing, an' tha merman don't generally sing at all. I've been trying ta teach myself, though."

"You're very good," Mark commented, folding his arms. Jack rubbed the back of his neck.

"Thanks."

"Just open your mouth a little more. Don't have such an iron jaw."

"Wait, ya sing?" Jack seemed honestly surprised by this, his eyes widening.

"Well, a little-"

"Sing!" Jack urged.

"What? Now? Sing what?" Mark replied, staring.

"Sing what I was just singing! Show me!" 

"Um... okay... I'm not very good, though. What were the lyrics again?" Mark asked, although he knew them. He was just trying to stall.

"Sailor, please, hear my call, drive yer boat but then ya fall, crying, dying, wish ya never came, but you'd end up like this anyway all the same. Sing that."

Mark took a deep breath, and then began to sing in his deep voice. 

"Sailor, please, hear my call,

Drive your boat but then you fall,

Crying, dying, wish you never came, 

But you'd end up like this anyway all the same.." 

Jack stared at Mark with wide eyes as the American closed his mouth. 

 "Dude, yer amazin'! If I didn't know better, I'd say yer an actual merman!"

"Heh.. thanks. I sing a bit at home, but not a lot." 

"Ya should sing more! Yer awesome!"

Mark turned pink and looked down at his feet, dangling in the water. The two fell into silence as Mark thought and Jack swam.

After a little while, Jack swam close up to the rocks and rested his head and arms on them, looking up at Mark. 

"Why don't ya come swimmin'?" he asked, head resting on his arms. Mark shrugged and looked away awkwardly. 

"Didn't I tell you?" he said, sighing. "I can't exactly swim."

"Oh, is that all?" 

Jack laughed as he twisted away from the rock and span in the water, sending small sprays at Mark. 

"I can teach ya ta swim, if ya want." 

"Really?!"

"Yeah, sure. I mean, I'd like ta think I'm pretty good. Tail an' all." Jack giggled, and Mark laughed. 

The two of them talked for the next few hours, Mark sitting on the rock, Jack swimming in the ocean, both of them confined to their own space. By the end of the time, they had formed a solid bond, a good friendship. 

* * *

The next day, Jack was swimming up to the rocks, when a soft song floated to his ears. Slowing down, he recognised the voice. 

Mark.

He was singing the song Jack had taught him, sitting on the end of the rock line with his knees tucked up to his chest and his eyes closed. 

 Jack dived under the water and opened his eyes, seeing bubbles rush past him. The song was distorted by the water, but he could still hear it, just enough for it to be beautiful for him.

Mark sounded like he should be the merman, not Jack. And for the first time, Jack questioned whether he deserved to be a merman at all. He was too pale, and he couldn't sing well, and he-

And he should stop thinking like this, that's what he should do.

But as his mind drifted, he couldn't help thinking. Mark was built like a supermodel, muscled, strong, fit, tanned. He had a beautiful singing voice, and Jack got the feeling he could do nearly anything he wanted. 

Meanwhile, Jack was a pale Irish merman with a voice that was too high and no muscles. They were so different, and-

"Jack?"

Without realising, Jack had floated upwards and was now floating by the rock, his scaly tail refracting the sun.

"Oh, I was just, uh, thinkin'..."

"About what? What was so important you forgot to keep spying?" Mark laughed, and his eyes twinkled. Jack shook his head.

"Um... nothin'."

"Come on, tell me!"

"I was just thinkin'," Jack blurted out. "Yer so perfect an' muscly an' so good at singin', an' I'm such a pale mess, you'd make a much better merman..."

Mark laughed, the deep sound vibrating through the air. The sound was almost as sweet as his singing.

"Aw, you're a great merman, Jack! Don't worry about it!"

After that, Mark began to ramble on about something else, and Jack lost track, nodding only when he needed to. He was lost in his thoughts, and he needed some time.

Maybe he was developing the slightest little crush on this human, this one with legs. But he didn't have legs. He had a tail. And neither of them could enter the others domain. 

If only Mark really  _was_ a merman, Jack sighed to himself.

**Notes for the Chapter:**

> This went everywhere in this chapter lmao XD I quite like it, I think it ended at a good point, so I hope you enjoyed too! :D


	4. Swimming Lessons

**Summary for the Chapter:**

> Jack attempts to teach Mark to swim.

**Notes for the Chapter:**

> I'm writing this on the train to comic con!! I'm going as Natsu and I'm so excited! This is gonna be a short chapter because I want it to be posted before I get there, but here we go again!

"Okay, so firstly you have to make sure you're okay with this."

Mark nodded, kicking the water. Jack swam around him, holding his arms out. 

"Now, just try and fall into my arms."

Taking a deep breath, Mark slid from the rock into the water, gasping at the cold. Jack wrapped his arms around him and they floated in the water. 

"I can hold you until you're comfortable with the water, so don't worry."

Mark took another deep breath and tried to calm his racing heart. Jack pulled him closer and Mark felt his heart speed again. 

"I don't have to do this, but humans have legs, so you gotta kick them."

"I wish I was a merman," Mark gasped as he kicked his legs frantically. The world was blurry, as he had left his glasses on the rock, and all he could feel was the rush of water against his skin and Jack's strong arms encircling him. 

"I wish you were too," Jack thought bitterly, but didn't say it out loud. Water splashed at his face from Mark's desperate kicks, and he wiped it away. 

"Just relax, don't be scared. You're safe, I got you."

Mark nodded, slowing down his kicks at the same time as his heart rate sped up. He felt Jacks arms tighten protectively. 

"Better. Now start moving your arms. You've seen humans swim before, right?"

"Yeah, of course." Mark began to move his arms, but lost his balance and plunged face-first into the cold water. Jack pulled him up immediately, but he began hyperventilating. 

"Cold, cold, cold, dark, dark, scared.." he was muttering, and Jack placed him back onto the rock, pushing his glasses back onto his face. Mark shivered, and looked down at Jack. 

"Thank you," he said quietly. Jack smiled and dived backwards, swimming around in the water before leaping out and doing a flip. 

Mark laughed, leaning back on his hands and kicking his legs. He watched as Jack swam around, spinning and jumping and flipping over. He clapped whenever Jack did something, and the Irish merman continued to entertain.

The sun sparkled as it hit the water, illuminating the two men. Jack giggled as he floated up to Mark on his back, and the two started talking about whatever came into their heads. 

It was almost as if nothing divided them. 

**Notes for the Chapter:**

> Well this wasn't posted anywhere NEAR when I wanted it to be, but oh well! Comic con was amazing! I got an awesome Fairy Tail poster and Undertale poster, and a Papyrus badge for my bag! It was awesome, and I finally got around to finishing this, lmao. Its probably not gonna be that long (rip) because I don't really know what to do.   
> I hope you liked!


	5. I Was Trying... For You

**Summary for the Chapter:**

> Jack comes back to the rock to find something he definitely didn't expect.

**Notes for the Chapter:**

> I've pretty much decided the plan of events for this fanfic, but I don't exactly know the specifics of how many chapters there will be. Probably around 10 or 11 in the end, which means we're already halfway through our little merman adventure ╥﹏╥
> 
> I hope you're enjoying it, though!

Floating lazily along on his back, Jack flicked his tail idly and stared at the clouds. The waves moved softly around him, and he allowed his body to be moved by them, creating his own peaceful little bubble. 

Sighing, Jack closed his eyes and just let himself be rocked gently by the waves. The sun shone brightly, warming his face and the ocean around him. 

 _This,_ Jack thought dreamily,  _this is what life is all about. Just floating in the sea and enjoying life._

The merman flipped over so he was floating on his stomach and watched the fish swimming by happily. The clear waters let him see all the rainbows of undersea life, and yet his back was still warm from the sun. 

 _I wonder how many humans would love to have this ability,_ he thought, his tail swishing moodily. 

Just then, he heard splashing and a familiar voice calling for help. Looking up, Jack saw the rocks where he always met with Mark, not far from him. There was someone splashing by the rock, water flying everywhere. 

Cursing under his breath, Jack dived under the water in order to swim faster and began hurrying towards the rocks. He had a pretty good idea of who the one by the rock was, and he muttered under his breath angrily. 

When he reached it, sure enough, it was Mark, floundering in the water like a dying fish. He was calling out for help, and his limbs were flailing everywhere, splashing water into Jacks eyes as he approached. 

"Mark, calm down! I'm here!" he yelled over the splashing of water and Mark's cries for help. The older didn't seem to hear him, though, continuing to flail and call out. 

"Mark! Stop it!"

If anything, Mark's movements became more chaotic and stressed, his cries getting louder. Jack attempted to swim closer to him, but was greeted with Mark's flailing arm whacking him square on the nose. 

The contact seemed to make Mark realise he had company, as he turned around to see Jack rubbing his nose impatiently. Relaxing, he allowed Jack to scoop him up and plop him back on the rock. 

Once he was safely on the rocks, glasses firmly on his nose and no chance of falling off, Jack began to swim back and forth, like he was pacing. 

"What tha FUCK were ya doing? I thought ya said ya didn't wanna swim any more?" 

Mark looked at his lap, scratching his thigh. 

"I wanted.. I wanted to learn to swim on my own, so that I could impress you..."

Jack's face softened, and he looked at Mark in slight confusion.

"Ya wanted ta impress me?" he asked quietly, smiling a little. 

Mark nodded, and Jack shook his head. He swim close to Mark and touched his nose, giggling a bit. 

"Next time, don't put yourself in a situation of potential death. That won't impress me, that'll annoy me. Because then I have to save your human ass."

Mark nodded and sighed, twisting his hands around. Jack noticed his discomfort and tilted his head questioningly, eyes wide with confusion. 

"Mark? What's wrong?"

Mark avoided the merman's eyes, instead staring at a random point on the horizon. Jack swam closer, until he was essentially in Mark's lap. 

Without warning, Mark slid into the water and wrapped his arms tightly around the green haired fish boy. Shocked, Jack slowly reached out and encircled Mark's waist. 

"I'm sorry." Mark sobbed, leaning on Jack's shoulder. Jack softened and smiled. 

"Don't be. I'm glad I met you. You're the best friend I have, to be honest."

Mark giggled slightly as a tear rolled down his cheek, dripping into the sea to join the rest of the salty water. 

The two remained floating in the water, Jack keeping them upright, locked in a tight embrace. 

**Notes for the Chapter:**

> Yay! Some soft little kind of feels at the end there for you, because I haven't written feels in ages (rip)


	6. Jack...

**Summary for the Chapter:**

> A storm is brewing...

**Notes for the Chapter:**

> GAH its been forever I apologise I've been very busy with school and anxiety and depression and shit but I'm coping and I'm finally back! Did y'all miss me? You know you did. 
> 
> Take this! The next part of our fishy exploration!

"Jack.."

"Don't try ta sweet talk me!"

"I was just trying to be nice!"

"Nice? NICE?! HOW IS ALMOST DROWNING YERSELF NICE?! I TOLD YA NOT TA DO THIS!"

"I'm sorry.. I just thought... I thought if I could come see you we could talk more..."

"WE'VE FUCKING TALKED ABOUT THIS! YA CAN'T SWIM!"

"You're meant to be teaching me!"

"YER NOT MEANT TA FUCKING DROWN YERSELF! THE WAY YER GOING, YOU'LL NEVER SWIM! EVER!"

"Well maybe I would be able to if I didn't have such a shit teacher!"

"MAYBE YA WOULD BE ABLE TO IF YA WEREN'T A FUCKING IDIOT! MAYBE ITS A GOOD THING THAT YOU CAN'T SWIM!"

Mark stood up abruptly. His voice changed from anger to danger and his fists clenched.

"What the fuck does that mean?"

Jack flicked his tail angrily, swimming around a little. Truth be told he didnt exactly have an idea of what he meant by that but he wasn't gonna let Mark know. 

"It means maybe I would be better off having never met ya. Maybe then I wouldn't have ta get stressed about saving yer dumb ass every other day."

Mark furiously wiped away a tear threatening to spill and went to reply, but found his voice was choked by emotion. 

"AND YA KNOW WHAT, MARK? YA CAN CRY ALL YA WANT WHEN YER DROWNING IN THE OCEAN. I'M FUCKING DONE."

Glaring at Mark, Jack turned around. He began to swim away while Mark held back his tears.

"I'm sorry, okay?" Mark whispered under his breath. Jack didn't hear, continuing to swim away and diving underwater.

From Mark's vantage point above the water, though, he could see what Jack couldn't.

A large boat sailing slowly towards the rocks, dragging a large fishing net with them.

Directly where they could catch Jack in the net without him seeing until it was too late.

"Jack!" Mark screamed, desperately trying to make Jack hear him. "Fucking listen!"

No sign that Jack had heard, let alone that he acknowledged the other man.

"Fucks sake, Jack..." Mark cursed, unable to do anything but sit and watch. 

 It wasn't long before muffled, bubbling screams started erupting from where Jack was, and the ship began to drag its net onto the deck.

"WAIT!" Mark screamed, trying to make someone, anyone, hear him. A couple of people glanced over, but nobody reacted. He was forced to watch as Jack was pulled out of the water along with some innocent fish, and the people on the boat began to scream in excitement that they had caught a merman.

"LET HIM GO! PLEASE!" Mark yelled. He could already tell the lack of water was affecting Jack. He didn't know what would happen if Jack was fully out of the water for too long, but he couldn't imagine it would be good.

The boat began to slowly turn, and Mark knew he would lose Jack if he didn't go. Even from a distance, Mark could tell Jack was suffering. It broke his heart to see Jack being pulled up onto a boat by a net and talked about cruelly like he was just some common fish.

Mark stood on the rocks almost paralysed as the boat sailed away. He knew where it was headed, and he knew he had to get there, but his legs refused to move. His eyes filled with tears again.

What if Jack didn't make it, or he was sold like an animal, or dissected for science? And the last thing he remembered of Mark was an argument?

He wouldn't even get to say goodbye.

"Jack..."

**Notes for the Chapter:**

> WOWIE I HAVEN'T POSTED IN MONTHS OOPS DID YOU MISS ME? I MISSED YOU MY FRIENDOS TAKE THIS NEW CHAPTER I HOPE I'M GONNA BE ACTIVE NOW I HAVE IDEAS AND I NEED TO UTILISE THEM SO NYOOM SSS OUT


End file.
